ANSWER: 20 Jan 2006
Hi Mark,
We are writing a response to your question relating to location of native
Australian plants which can adapt to high levels of lead (700 - 810 mg/kg)
or copper (21-31 mg/kg) within the soil. By searching the web we managed to
find two plant species that are native to Australia that can tolerate high
levels of lead or copper.
According to http://www.ansto.gov.au/discovering_ansto/media_centre/discover_more_science_stories/sciences
tories/plants_that_can_accumulate_toxic_metals Stackhousia tryonii (Batianoff et al. 1990) and Hybanthus floribundus (Cole
1973) are the two Australian native serpentine-endemic and nickel indicator
plant species that have the potential for use in Ni [and possibly lead]
phytoremediation/phytoextraction.
These species possess a unique ability to hyperaccumulate metals such as Ni,
Zn, Pb, Cd, Cu, Co and Mn - to extremely high concentrations in their shoots
without showing any symptoms of toxicity. Stackhousia tryonii is a
serpentine-endemic, rare, native Australian plant and is reported to
hyperaccumulate nickel up to 55,500 mg g-1 on a dry weight basis (Bhatia and
Ashwath, 2002).
References:
Bhatia P and Ashwath N (2004). Somatic embryogenesis in the nickel
hyperaccumulating shrub, Hybanthus floribundus (Lindl.) F. Muell. Plant
Tissue Cult. 14: 1-7.
Bhatia NP, Walsh KB, Orlic I, Siegele R, Ashwath N, Baker AJM (2004).
Studies on spatial distribution of nickel in leaves and stems of the metal
hyperaccumulator Stackhousia tryonii (micro-PIXE) and EDXS techniques. Functional Plant Biology 31, 1061-1074.
We emailed Dr Nanjappa Ashwath at Central Queensland University (n.ashwath@cqu.edu.au) to ask for further info as to availability of these
plants in your area and were advised that Stackhousia tryonii only occurs in
Central Queensland but that Hybanthus floribundus is found in Western
Australia.
Since that left us with only one species, we decided to email Men Of The
Trees Western Australia - Headquarters, St Barbe Grove Nursery Hazelmere -
contact@menofthetrees.com.au - (but Ross the manager didn't know of any
copper or lead tolerant plants) and join a forum and post your query on
OzPlants (Australian Native Plants) Forum of Garden Web, based in the USA - www.au.gardenweb.com/forums/oznative/
- and phone a few potential sources of
further information. We spoke to Frances Borland who has worked on the
revegetation of contamination around the Broken Hill lead mine and Frances
said:
"a Masters student from University of NSW whose name I can't remember, from
Earth Sciences or Geography was working on which native plants tolerate
lead. We found most drought tolerant native plants tolerate heavy metals but
not low pH (acidic) soil. Perilya [the owner of the Broken Hill lead mine]
may also know about species for revegetation. I'm not sure what effect
copper has on plants. If you have to separate metals from ore you have to
use a lot of acid so it can be a challenge to grow stuff where the tailings
damns are. On Block Tin Flat behind the RSPCA we couldn't establish plants
on one area and found that it was pH 6.5 (most of the native range plants
that we grow here are used to pH 8-9) so we added lime and green mulch from
the Council and 4-5 semitrailers of hay from someone's mowing. They took a
lot of topsoil off from there 20 yrs ago when they built a local road and
the soil was compacted by circuses and sports activities so water would
brush off when it rained so we put miniature ditches across the slope of the
land so the water would gather and seep in then planted salt bushes as the
coloniser plants then the normal rangeland plants were able to grow. I
suspect the copper might be more of a problem than the lead if the copper if
very high. Any of the mining companies should have info on how to get plants
to grow in heavy metal contaminated soil." [End of phone conversation]
A websearch among University of NSW theses, for the student who might have
worked at Broken Hill revealed:
ref:
Author: Boominathan, Rengasamy. Title: Study of heavy metal tolerance,
accumulation and recovery in hyperaccumulator plant species (2002) xxvi,
191 leaves, bound : ill. (some col.). Dissertation Note: Thesis (Ph.
D.)--University of New South Wales, School of Biotechnology and Biomolecular
Sciences.
I contacted Rengasamy Boominathan's lecturer, Dr Pauline Doran
(p.doran@unsw.edu.au) who advised me that:
Rengasamy did not do any research in Broken Hill although a University of
Western Sydney (UWS) student called Abdul Kahn was studying plants that can
tolerate motor vehicle emissions around 1999 & he possibly went to Broken
Hill but I'll research it and in the end you may have to ask Alan from
Melbourne University for a list of native plants [a week later, Dr Doran
concluded Dr Alan Baker was the best person to contact].
In the meantime, a websearch on Abdul Kahn did not reveal his work so we
looked at our list of Australian lead mining companies:
1. BHP Billiton www.bhpbilliton.com
2. Perilya www.perilya.com.au ph 0880888582.
3. Xstrata www.xstrata.com
4. Zinifex www.zinifex.com
5. Consolidated Broken Hill (CBH) www.cbhresources.com.au
6. Magellan Metals - owned by Ivernia West Inc www.ivernia.com
Welshpool, WA
ph 0892677000
7. Kagara Zinc Ltd www.kagara.com.au/default.asp
West Perth, WA ph
0894811211
and decided to call a Perth-area one - Kagara Zinc Ltd, but was informed
that this lead mine does not work with any plants, but they suggested we
contact 07 40974100 (Environmental Dept of the Processing Plant for Kagara
Zinc at Mt Garnett, Queensland) and talk to Jacinta Haire who might be of
help. Calling this number Jacinta said they may only be of help by researching
the issue in the future because they are quite a long way away from needing
information regarding the soil and plants and they suggested we check the
website of ACMER (Australian Centre for Minerals Extension and Research).
Finding nothing on the ACMER website - www.acmer.com.au - we spoke to
Professor L Clive Bell of ACMER who kindly sent us a booklet by the now
defunct Ameef (Australian Minerals and Energy Environmental Foundation),
entitled: "The Responses of Plants to Metal Toxicity - A review focusing on
Copper, Manganese and Zinc" Author S. M Reichman (2002).
Section 6. "Metal Toxicity and Australian Native Plants" on page 40-1 of the
booklet states:
"Australia has many unique species of plant, and so, it is likely that
Australian species would have different tolerances and responses to excess
metal than exotic species. Unfortunately, this subject has received little
attention....
"Metal toxicity issues in plants and soils are a significant problem
throughout the world, including Australia. It is only by understanding the
relationships between bioavailable metal fractions in the soil and plant
responses to metals that we can make decisions regarding metal toxicity in
plants. At present, research has still not conclusively defined the
bioavailable metal fraction nor do we fully understand the processes behind
metal toxicity responses in plants. As well, many poorly designed
experiments have been undertaken, where confounding effects such as that of
pH on bioavailability in soil, or precipitation of metals in solution
culture, has reduced the precision of and confidence in results obtained.
Little research, particularly of a quantitative nature, has been undertaken
on Australian plants. If we are to understand the effects of excess metal on
Australian plants it is important that well designed, quantitative research
be undertaken. This will enable the rehabilitation of metal contaminated
areas with appropriate Australian species, allow identification of metal
toxicities when they occur and allow for the effective regulation of metal
emissions."
So we decided to write to Dr Suzie M Reichman, Lecturer in Soil Chemistry,
Lincoln University in New Zealand (reichmas@lincoln.ac.nz) to ask if any
further work could provide a list of useful species. She emailed to suggest
we should contact Professor Alan Baker, School of Botany, University of
Melbourne & Editor-in-Chief (Inorganic Contaminants), International Journal
of Phytoremediation.
We emailed Professor Baker - ajmb@unimelb.edu.au - who wrote back to say he
had nothing to email but was happy for us or you to phone him (ph
0383445055). During the phonecall, Professor Baker said:
There has been a little bit of experimental work done on lead but what
people think is available to plants is usually not & the impact of other
soil conditions is more important especially pH & most of the lead on plants
is from deposition. I did a little bit of work on road verges but you can
virtually grow anything there but in Europe a type of grass called Red
Fescue was marketed as a cultivar called Merlin which was stress tolerant in
general and has some salt tolerances and was chosen because it grew on metal
mines but there has been very little done on Australian plants. There was a
little bit of work done at Port Pirie by a group at Newcastle University in
the Chemistry Dept. Some people talk of metal accumulating plants that can
be used in radiation shielding but I'm working more with the minerals
industry getting plants back onto sites. I never worried too much about lead
uptake into plants until a Thai student started working on lead carbonates
(rather than the usual lead sulphates) found around a lead mine in Thailand
near the Burmese border. There is an Environmental Pollution paper on it
coming out soon. Other people have found on rifle ranges in the right sort
of conditions like eg acid rain that the lead becomes bioavailable and we've
found some plants improving their lead tolerances over time. One of the
Victorian gold mines which is now a Commonwealth Games shooting range has
some lead but more of an issue with arsenic contamination. Lead is one of
the first areas studied in the relatively new field of ecological genetics
but lead is very hard to keep in solution and lead really switched me on to
my interest in metals. Soil is a very good sink for lead and as long as it
doesn't move out of the soil eg into sediments, then it is relatively
manageable. I met some people from the Lead Development Association (LDA) in
England and did some work with the International Lead Zinc Research
Organisation (ILZRO). The whole thing is about getting stabilisation
chemically internally in the soil and biologically using the right plants on
the top that don't translocate metals from the roots to the leaves etc.
Generally, grasses are the best at keeping metals in their roots. Strongly
rhizomatous and creeping grasses are the best for the physical stabilisation
of the soil and we're working with the gold mining industry on researching
the best ones of these.
[End of phone conversation]
We had requested to receive emails direct from OzPlants but had not received
any responses from the forum, so realized the direct email option may not
have been working and found the following four responses had been received
on the forum website:
Follow-Up Postings:
RE: Copper and lead tolerant native plants
a.. Posted by: nathanhurst VIC Aust on Fri, Feb 10, 2006
I don't really have any experience, nor read anything, but I have a
hunch that some of the juncus and other margin type plants might be good. An
ideal plant would grow quickly, collect and concentrate the wanted metal,
survive heavy pruning (i.e. mowing) and withstand the heavy metal,
waterlogging and drought. Halosarcia and atriplex are worth a look in too.
Juncus is easy to propagate from seed, atriplex (old man salt bush) is
readily available as a cattle food.
On the other hand, I know that earthworms are very effective at site
remediation. The idea is to grow lots of earthworms in the affected soil,
then bring them to the surface and collect and incinerate them. There was a
tailings extraction process using this for lead, copper, zinc, cadmium
(those metals are often connected with smelters). Check the ANSTO website.
[End of OzPlants forum responses]
From the ANSTO link we found an article
which, when
combined with Professor Baker's insight about the need to find plants which
keep the heavy metals in their roots, virtually knocks out Stackhousia as a
useful plant to you, IF there is a chance that animals will graze on the
plants you grow in your catchment area. Worryingly, the article states:
"The obscure Stackhousia tryonii plants look like a "bunch of stems with
narrow leaves", said Dr Naveen Bhatia, a researcher from ANSTO.
"Growing naturally in serpentine soils, they have a bad reputation among
farmers. If cattle eat these small herbs they get sick and can die."
Hopefully, there is enough information above for you to do some
experimentation or perhaps you would prefer to follow up on some of the
contacts first but either way, we'd be very grateful if you could let us
know how you go and in this way you could probably usefully add to the very
small amount of information there seems to be in this field.
Best of luck.
Yours Sincerely
Shahilla Balachandran and Hasibah Keriwala, Volunteer Information Officers
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